1. Field of the Invention
This invention relates to a method of producing a highly purified oleic acid from an oleic acid containing fatty acid mixture.
2. Description of the Prior Art
Oleic acid (cis-9-octadecenoic acid) is a typical unsaturated fatty acid constituting natural fats and oils or biological lipids, which is a very important substance in industry and biology.
It has been confirmed recently that highly purified oleic acid is colorless and odorless, excellent in the stability, high in the safety and has many excellent physical, chemical and physiological properties. Thus, such an oleic acid is actively and widely applied to fine chemical fields such as the life science of pharmaceuticals, cosmetics and foods, bioscience of biosensors and biosurfactants, electronics for simulation of biological function and so on as well as for presently developing high technologies.
However, commercially available oleic acid includes fatty acid homologues having different carbon numbers and double bond numbers, and has a purity as low as 60-90%. In addition, commercially available oleic acid also contains various minor impurities. Therefore, the commercially available oleic acid is unsatisfactory in the qualities such as color, odor, stability, safety and the like and can not adequately develop performances inherent to oleic acid.
As a method of increasing a purity of the fatty acid, there have generally been known various methods such as solvent separation, emulsification separation, urea separation and the like from the past. Recently, chromatographies using an adsorbent, an ion exchange resin and the like have been used. However, these methods are unsuitable in view of separation and refining levels, production capacity, production cost and the like as an industrial means for producing highly purified fatty acids.
Moreover, there is a method wherein the purity of oleic acid is increased by subjecting polyunsaturated fatty acid such as linoleic acid, linolenic acid or the like to a partial hydrogenation. However, this method has a problem of producing positional and geometrical isomers.
As the demand for oleic acid is increased with the diversification of applications, it becomes important to provide an oleic acid having high purity and high quality.